Organotinoxy substituted polysiloxanes



United States Patent 3,384,648 ORGANOTINOXY SUBSTITUTED POLYSILOXANES Kazuo Itoi, Kurashiki, Japan, assignor to Kurasliiki Rayon Co., Ltd., Kurashiki, Japan No Drawing. Filed Oct. 15, 1965, Ser. No. 496,695 Claims priority, application Japan, Dec. 26, 1964,

5 Claims. (Cl. 260-4295) ABSTRACT on THE DISCLOSURE Vinyl chloride resins are stabilized to provide increased weather resistance, low hygroscopicity and some water repellency by adding thereto up to 1 percent by weight of a liquid polysiloxane compound characterized by structural units in the main chain having the formula wherein R is an alkyl radical having from 1 to 12 carbon atoms, there being no linkage of ESlH in the molecule.

A novel polysiloxane compound for this purpose is prepared by the reaction of tri-(n-butyl)tin oxide with methylhydropolysiloxane in equimolecular proportions and separating the volatile tri-(n-butyl)tin hydride reaction product from the heavier liquid polysiloxane compound.

The present invention relates to a stabilizer for vinyl chloride resins comprising a liquid polysiloxane compound having a structural unit of the formula wherein R is an alkyl radical having 1 to 12 carbon atoms, in the main chain of polysiloxane but no linkage of ESlH in the molecule.

Ordinarily, there has been seldom reported a compound having such a linkage of ESl-O-SHE, but only a report that a compound of R SnOSi(CH was obtained by co-hydrolysis of a compound of R SnCl with trimethylchlorosilane was published by Ohkawara and others at the XIV Annual Assembly of the Chemical Society of Japan (cf. Abstracts of Lectures at the XIV Annual Assembly of the Chemical Society of Japan, p. 321).

As ESl.Cl linkage is apt to be hydrolized to form siloxane linkage, it is difiicult in the said method to ob tain such a compound as described in the present invention having OSnR on the branched chain of polysiloxane. The object of the present invention is to provide a very effective stabilizer for vinyl chloride resins, and more particularly, a stabilizer for vinyl chloride resins 3,384,648 Patented May 21, 1968 ICC consisting of a liquid polysiloxane having the structural unit of in the main chain of polysiloxane.

The inventor has found that a polysiloxane compound having an optional proportion of the structural unit of (7H3 (Si-O) Sn s in the main chain can be easily obtained by the equimolar reaction of a silane compound having an optional proportion of the structure of H in the main chain of polysiloxane with (R Sn) O, because the following reaction is carried out quantitatively at room temperature or a lower temperature without using a catalyst and a solvent.

The present inventors further research has resulted in finding that, the polysiloxane compounds having the structure i (Si-O) OSHR:

while having no SiH linkage in the molecule produced as described above is very effective as a stabilizer for vinyl chloride resins.

More precisely, when the ratio of ESi-OSnE linkage of the structural unit of the present invention,

in the main chain of polysiloxane is less than 10 mol precent, it is necessary to add a large amount of the stabilizer due to its descreased stabilizing etfect on vinyl chloride resins, so that it is preferable to contain more than 50 mol percent. When ESl-H linkage is contained in the stabilizer, the said linkage is not stable, so that it is reacted with R SnOSiE linkage to form siloxane linkage as shown in Table 1 and Formula 3, on blending with vinyl chloride resin at a high temperature and disadvantageously R SI1OSlE linkage is not only lost but also a three dimensional insoluble and infusible resin is formed, which is hardly blended homogeneously with a vinyl chloride resin.

Methylhydropolysiloxane was mixed with tri-n-butyltin oxide (n-Bu Sn) O with various molar ratios and distilled under a reduced pressure in nitrogen stream in an oil bath at a temperature from C. to C. The result is shown in Table 1.

TABLE 1 N o. of experiment 1 2 3 4 5 6 Polysiloxane/(n-Buasn)2O molar ratio 1.0..

Yield of n-Bu SnH(percent) e 43.6

Degree of cross-linkage of polysiloxane b Degree of cross-linkage per molecule of polysiloxane 0 5." 3. v State of distillation residue Liquid Liquid Solid Solid Solid. Solid.

(F113 (I311; ([3113 $11: (3 3 3 Structural unit of distillation residue SliO- -SiO-Si0 -SiO- Si0?i0 0 Sn O l H I I 0 S11 l (3113 -S1O (3H -?iO-Si- CH3 SiO-SIi-O CH3 (I) CH H a The yield is the value based on tin according to formula (2). b Degree of cross-linkage is shown by the number of Si atoms cross-linked by crosshnkage reaction per 100 of Si atoms. a It is the value as presuming the degree of polymerization of methylhydropolysiloxane being 50.

d The number of moles of methylhydropolysiloxane was calculated on the basis that one unit of As seen in Table 1, in the molar ratio of l, the following reaction occurs,

and in the molar ratio of 2, the following reaction occurs,

I R3sn)z0 2n-i 'i-oHa 2R3SHH CH -bii-O-SFCH I I I and under the above reaction condition, it is apparent that the following reaction occurs.

R snH CH -S i-O-S l--CHs J) I I Thus, a resin having cross-linkage is obtained.

On camparing the experiment No. 2 with those of Nos. 4 to 6, an interesting fact was found; that is, in Nos. 4 to 6, the compounds were solidified by 3 cross-linkages per macro-molecule, but in N0. 2, though a half of siloxane was cross-linked, the compound was still liquid. The reason of the above fact is as follows: in the experiments of Nos. 4 to 6, as Si adjacent to the crosslinkage is bonded with hydrogen, three dimensional linkage is caused by an irregular reaction due to lack of steric hindrance, but in the experiment of No. 2, all the hydrogens are converted into and OSnR radicals are always attached to Si adjacent to the cross-linked Si alternately in the opposite side due to steric hindrance.

It is considered due to the fact that on reaction of the tin compound with is one mole.

C Ha 811R;

I (a... a.

Polysiloxane having such azSi-H linkage is cross-linked to form a three dimensional structure, and an insoluble and infusible resin is produced, so that it is disadvantageous that a stabilizer contains such a resin, and it is required to remove the resin by a complete reaction. It is very advantageous that the stabilizer of the present invention is hardly gelled as described above, and it is easily blended with a vinyl chloride resin, as ESi-O-SHR is cleaved with water or some other content to form a siloxane linkage and keeps it in the liquid form, if crosslinked.

As the stabilizer of the present invention is usually colorless, transparent and liquid, when it is blended with a vinyl chloride resin, the resin is also colorless and transparent. Therefore, it can be used as a stabilizer for transparent polyvinyl chloride products as publicly known stabilizers of an organic tin series. As the stabilizer of the present invention is stable for heat and possesses siloxane linkage and -=-Sn-OSiz linkage of a low vapor pressure, it is not decomposed by heat or seldom yields disappearance by an elevated temperature, on blending with a vinyl chloride resin. When using the present stabilizer, there can be obtained a vinyl chloride resin possessing an improved Weathering resistance with a low hygroscopicity and some water repellency due to the polysiloxane linkage. The present invention is illustrated by the following example.

EXAMPLE (1) Synthesis of the stabilizer.0n mixing equal moles of tri-n-butyltin oxide and methylhydropolysiloxane (taking 60 g. as 1 mole) while cooling, an exothermic reaction occurred. When distilling the product in nitrogen stream under a reduced pressure of 5 mm. Hg, tri-n-butyltin hydride formed was distilled off at temperatures near 105 C. and the yield was more than The distillation residue was a colorless and transparent liquid, and

6 according to the infrared absorption spectrum, there was CH3 observed the absorption of ESllO-SiE at 960-980 cmf l and it was found that a compound of S1 O) O-SnR; E 5 wherein R is an alkyl radical having 1 to 12 carbon atoms, in the main chain of polysiloxane and no ESi-H linkage OSn(n Bu)3 in the molecule, which is obtained by reacting a poly- I siloxane selected from the group consisting of methyl hy- Was contained. (nBu represents a n-butyl radical). drogen polysiloxane and methyl hydrogen siloxane-di- (2) Estimation of stabilizing efject.-After 100 parts methyl siloxane copolymer with an organotin compound of a commercial polyvinyl chloride (Alon P=800), 10 having the general formula (R Sn) O, wherein R has the parts of dioctylphthalate and a required amount of the same meaning a de ibed b stabilizer were blended with a mixing roll at 150 C. and 2. A stabilizer a et forth in laim 1 wh r i th polypre-heated at 150 C. for one minute, and it was pressed siloxane compound contains more than 50 mol percent of for one minute under a pressure of 50 kg./ cm. to form a the structural unit represented by the formula set forth in plate for making specimens. These specimens were put in claim 1. a gear-oven at 180 C. and heat-treated for a given time, 3. A stabilizer as set forth in claim 1 wherein R in the and the degree of coloring was observed by eyes to decide polysiloxane compound is n-butyl. the grade, by which the stabilizing effect of the stabilizer 4. A stabilizer for vinyl chloride resin which comprises was estimated. The result is shown in the following table. a liquid polysiloxane compound substantially consisting Stabilizer Stabilizer of the Dibutyl tin dilaurate Lead Calcium B i present invention stearate stearate stearate Heating time at 180 0. Added parts l 0.3 1 0.3 1 1 1 (min.)

Mixing time by a mixing roll (miIL) 4 2 2 2 8 2 2 0 Color Colorless. Colorless" Colorless... Colorless White Pale orange P31 Orange,

rade of coloring. 1 1. 15 C or .r Pale yellow Yell0w Pale yellow- Yellow Slightly yellow Orange R d,

Grade of c01o1'ir1g 5 7 4 1. 0101' Yellow Brown Yellow Black brown Pale yellow Dark 0range Dark r d,

Grade of coloring 6 2 5 1 7 4 3.

, of a homo ol mer of a structural unit re resented b the As seen from the above result, the order of colormg f ul p y p y is, lead stearate the stabilizer of the present invention dibutyltin dilaurate calcium stearate barium stearate CH3 and the stabilizer of the present invention shows a little Si0 better eifect than commercial butyltin dilaurate and is useful in ractice. 4O

(3) Trgnspm ency For comparing transparency on wherein R is a n alkyl radical having 1 to 12 carbon atoms. the specimens obtained in (2) before and after heat-treatf' 532 23;; g fi i i wherem R m the ment, each specimen blended with dibutyltin dilaurate p y p n 15 u y and the stabilizer of the present invention Was transparent R efer C but the specimens blended w1th stearates were not. ences lted Whatl claim is: Hiroshi Kataoka, Chem. Abstracts, vol. 55 (1961),

1. A stabilizer for vinyl chloride resins consisting es- P- 10319- sentially of a liquid polysiloxane compound having more than 10 mol percent of a structural unit represented by TOBIAS LEVOW Pnmary Exammerthe formula, W. F. BELLAMY, Assistant Examiner. 

